Bilingualism and second language learning always involve the interaction between two language systems or subsystems. When young children acquire language, often there is more than one. Considering the modern era, as the Vietnamese language has expanded geographically and culturally, coming into contact with other language communities, all of the different combinations of acquisition, learning and unlearning have come into play. These include, today, perhaps for the first time in recent history, language interactions that include first language attrition. This progress report of tentative results from our project compares the bilingual learning circumstances in two studies (in Taiwan and in northern Vietnam) where one language is in ascendence and the other may not be. The other language may be not developing at the same rate of progress or it may be undergoing replacement by the dominant language. In the larger project that encompasses the two studies, the Vietnamese language is part of the unfolding outcome of learning and attrition. On the other hand, it could become part of the process of potential recovery and stabilization of the minority language in some cases.